Scientists move a step closer to realising quantum computers

Published: Friday, June 27, 2008, 11:28 [IST]

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London, June 27 : Electrical and computer engineers in the US have created a hybrid molecule in which its quantum state can be intentionally manipulated, something that is considered to be a very necessary step in the building of quantum computers that can process exponentially more information than the existing machines.

Gerhard Klimeck, a professor at Purdue University and associate director for technology for the national Network for Computational Nanotechnology, has revealed that his team made this advancement while studying an experimental silicon computer chip.

"Up to now large-scale quantum computing has been a dream. This development may not bring us a quantum computer 10 years faster, but our dreams about these machines are now more realistic," Nature magazine quoted him as saying.

He says that one of the biggest challenges before researchers striving to realise quantum computers has been to create a computer semiconductor in which the quantum state can be controlled, creating a quantum bits (qubit).

"If you want to build a quantum computer you have to be able to control the occupancy of the quantum states. We can control the location of the electron in this artificial atom and, therefore, control the quantum state with an externally applied electrical field," he says.

Working with graduate student Rajib Rahman, Klimeck developed an updated version of the nano-electronics modelling program NEMO 3-D to simulate the material at the size of 3 million atoms.

"We needed to model such a large number of atoms to see the new, extended quantum characteristics," he says.

The simulation showed that the new molecule was a hybrid, with the naturally occurring arsenic at one end in a normal spherical shape and a new, artificial atom at the other end in a flattened, 2-D shape.

When the researchers controlled the voltage, they observed that they could make an electron go to either end of the molecule, or exist in a quantum state.

David Ebert, a professor of electrical and computer engineering at Purdue, and graduate student Insoo Woo later developed an image of the model.

Delft's Rogge says the discovery also highlights the current capabilities of designing electronic machines.

"Our experiment made us realize that industrial electronic devices have now reached the level where we can study and manipulate the state of a single atom. This is the ultimate limit, you can not get smaller than that," Rogge says.